#include <iostream>
#include <cstdio>
#include <algorithm>
#include <functional>
#include <string.h>
#include <set>
using namespace std;
#define endl '\n'
#define ll long long
#define ld long double
#define pi pair<int, int>
#define f first
#define s second
//solution
const int mod = 1000000007;
const int k = 3;
const int rv[k] = {1, 0, 1};
function<int(int, int)> f[k] = {
[](int x, int y){ return (ll)x * y % mod;},
[](int x, int y){ return max(x, y);},
[](int x, int y){ return min((ll)mod, (ll)x * y);}
};
struct segTree{
int l, r;
segTree *left, *right;
int val[k];
segTree(int a, int b){
l = a, r = b;
if(l != r){
int mid = (l + r) / 2;
left = new segTree(l, mid);
right = new segTree(mid + 1, r);
}
memcpy(val, rv, sizeof(val));
}
void add(int x, int v, int t){
if(x < l || r < x) return;
if(l == r){
val[t] = v;
return;
}
left->add(x, v, t);
right->add(x, v, t);
for(int i = 0; i < k; i++) val[i] = f[i](left->val[i], right->val[i]);
}
int qry(int a, int b, int t){
if(b < l || r < a) return rv[t];
if(a <= l && r <= b) return val[t];
return f[t](left->qry(a, b, t), right->qry(a, b, t));
}
};
const int mxn = 500000;
int n;
int *x, *y;
set<int, greater<int>> s;
segTree tre(0, mxn);
void addx(int a, int b){
if(a){
if(~-x[a]) s.erase(a);
if(~-(x[a] = b)) s.insert(a);
}
tre.add(a, b, 0), tre.add(a, b, 2);
}
void addy(int a, int b){
y[a] = b;
tre.add(a, b, 1);
}
int sol(){
auto it = ++s.begin();
for(; it != s.end() && tre.qry(*it, n, 2) != mod; it++);
ll b = *(--it), ret = 0, cur = 1;
for(; it != s.begin(); it--){
ret = max(ret, (ll)tre.qry(b, *it, 0) * tre.qry(*it, *prev(it) - 1, 1));
}
return ret % mod * tre.qry(0, b - 1, 0) % mod;
}
//end solution
//interaction
int init(int n, int *X, int *Y){
x = X, y = Y;
s.insert(0), s.insert(n);
for(int i = 0; i < n; i++){
addx(i, x[i]);
addy(i, y[i]);
}
return sol();
}
int updateX(int a, int b){
addx(a, b);
return sol();
}
int updateY(int a, int b){
addy(a, b);
return sol();
}
//end interaction
/*
//test
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
int n, q;
cin >> n;
int x[n], y[n];
for(int i = 0; i < n; i++) cin >> x[i];
for(int i = 0; i < n; i++) cin >> y[i];
cout << init(n, x, y) << endl;
cin >> q;
while(q--){
int t, a, b;
cin >> t >> a >> b;
cout << (!t ? updateX(a, b) : updateY(a, b)) << endl;
}
return 0;
}
//end test
*/
